Transmittance ratio of a compensator

Simplified formulas are given for the calculation of the transmittance ratio of a compensator. The measurement scheme based on these formulas has the following advantages: (1) the value of transmittance ratio is not influenced by the calibration error and imperfections of the polarizer, and (2) a prior exact calibration of the compensator and the analyzer is not required. It is shown that the relative calibration error between the compensator and the analyzer can be determined from the experimentally measured angles. The error analysis of the formulas is presented to provide an understanding to minimize the uncertainty of the final results. Finally the scheme has been applied to the calibration of a Babinet-Soleil compensator and the results are presented. © 1975 Optical Society of America.